1. Scope of the Invention
The present invention relates to image processing and more specifically to imaging structures having motion defined by a cycle.
2. Related Prior Art
Moving structures are difficult to image, especially if an imaging plane is set in space with the structure moving in and out of the imaging plane. This is especially difficult when a second periodic motion is added. For example, imaging of structures in a subject which is breathing causes a periodic motion of internal structures. This is further complicated by the beating motion of the heart if the structure is on, or near the heart. The beating of the heart is a complex compressional and twisting motion superimposed on the respiratory motion.
It is often desirable to acquire images of moving structures, such as in coronary angiography, where images are acquired of vessels in a beating heart. For image enhancement purposes, several images are averaged to reduce image noise, and improve visualization.
MR coronary angiography has typically been performed using either breath-held, oblique single-slice techniques, or respiratory-gated 3D techniques. Repeated breath holding may not be feasible for some coronary patients, and navigation techniques to date have not generally provided a robust method which works over a range of different breathing patterns in a variety of patients. Moreover, in both of these approaches, success or failure is often not apparent for some time after the start of imaging. The purpose of this study was to develop a robust, non-breath-held technique for coronary MRI based on adaptive averaging.
Currently, there is a need for an imaging method which creates clearer images of moving structures than previously possible.